P rated tires are supposed to be derated 10% for light truck use. But if you are on roads without sharp rocks with a relatively light camper, why would you need macho tires? It sounds like you are well within the load specs -- your camper is hundreds of pounds lighter than most. P tires usually get better mileage on pavement. I can see light truck tires needed for severe roads, with sharp rocks or where you need to air down a lot. Even airing down on many gentle gravel roads seems overkill.
When I was in mountaineering, the common advise was to use heavy boots. This was for ankle support and ease of walking over rocks. Then Ray Jardine wrote his book on hiking the Pacific Crest Trail using running shoes. Wow, the improvement in hiking miles per day went way up for me. I hever had problems with ankles or rocks, even with a heavy pack. Then I read more of his book and lightened my pack by half, and was able to double my original miles per day. It's easy to choose the most conservative solution, but it's not necessary in all cases.